1. Field of the Invention
The present invention generally relates to an information processing apparatus (e.g., a scanner, a printer, a multi-functional imaging apparatus) linked to a network that can exchange information (e.g., processing-required information, apparatus information) with the network, and a method of transmitting and processing information such as a packet on a periodic basis between the information processing apparatus and the network by transmitting a packet while maintaining a main control unit of the information processing apparatus in a low-power mode.
2. Description of the Background Art
With the spread of computer networks in office environments and elsewhere, information processing apparatuses (including, but not limited to, a scanner, a printer, a multi-functional imaging apparatus or the like) are typically linked to a network, such as a local area network (LAN), a wide area network (WAN), the Internet, and so forth, so that information processing apparatuses linked to the network can communicate with each other and exchange information via the network.
In such a network environment, one apparatus may transmit certain information or receive certain information from another apparatus via the network, in which the transmitted information may be used for a given purpose, for example indicating an apparatus status. In such network environment, information processing apparatuses may be devised that exchange information with other apparatuses via the network while themselves remaining in a low-power mode (also referred to as “lower-energy consumption mode,” “energy-saving mode” or “sleep mode”).
For example, JP-2006-270898-A discloses an image forming apparatus linked to a network, in which the image forming apparatus is designed to automatically transmit various packets to the network on a periodic basis under given transmission conditions while the image forming apparatus is set in a low-power mode, wherein such automatic transmission may be conducted by a specific device, for example.
Further, JP-2003-303080-A discloses an image forming apparatus linked to a network, in which the image forming apparatus may include a circuit configuration designed to respond to a status-request packet transmitted from the network using a hardware used as a network interface.
Further, JP-3773688-B discloses an image forming apparatus linked to a network, in which the image forming apparatus is designed to transmit data when the image forming apparatus receives a given packet.
The above-described configurations can be used to transmit apparatus information (e.g., apparatus status information) to the network when the apparatus is set to the energy-saving mode or low-power mode.
Although such configurations can enable apparatuses to transmit packets automatically to the network periodically while the apparatuses are set to the low-power mode, they may not be effective if certain types of information are to be communicated among apparatuses while maintaining the low-power mode for apparatuses. This is because the above-mentioned configurations are designed to exchange information in a relatively simple manner among apparatuses. For example, information may be transmitted from one apparatus to another apparatus in one-way direction (i.e., one-sided communication) automatically, or one apparatus may respond to a request from another apparatus in certain limited situations.
However, with advances in computer networks, apparatuses may need to communicate each other in a relatively sophisticated manner. For example, apparatuses may need to communicate each other in an interactive manner (i.e., interactive communication) for various situations while maintaining the energy-saving mode or low-power mode for the apparatus, and the above-described conventional configuration may not be effective for such interactive communication.
For example, dynamic host configuration protocol (DHCP) may be used to establish a connection between two information processing apparatuses linked to a network, in which one information processing apparatus may be referred to as a DHCP Client, such as an image forming apparatus (e.g., printer), and another information processing apparatus may be referred to as a DHCP Server, such as a server used for providing an internet protocol (IP) address to the DHCP Client. In such environment, the DHCP Client may transmit a first DHCP packet including one transaction ID to the DHCP Server, and then the DHCP Server may transmit a second DHCP packet to the DHCP Client in response to the first DHCP packet. If such communication can be conducted successfully between the DHCP Client and the DHCP Server, the DHCP Client may be assigned an IP address, and the DHCP Client may use such IP address to communicate with other apparatuses linked to the network.
However, for a variety of reasons, such IP address communication for the DHCP Client may not be maintained: For example, the DHCP Server may receive the first DHCP packet from the DHCP Client, and then processes the first DHCP packet in a proper manner and transmit the second DHCP packet to the network (first communication process). Yet, because of network error or the like, the DHCP Client may not receive the second DHCP packet, whereupon the DHCP Client determines that the communication was not established successfully. The DHCP Client may then re-transmit the first DHCP packet using the same transaction ID again to the DHCP Server so that a proper communication can be established. However, the DHCP Server determines that the DHCP Server has already properly responded during the first communication process and ignores a new request communication re-transmitted from the DHCP Client. As a result, the DHCP Client is unable to use the IP address set in previous communication and must transmit another DHCP packet using a new transaction ID that is different from the previous one.
When changing a transaction ID in a conventional configuration, an operation mode of the DHCP Client (e.g., image forming apparatus) may need to be shifted from a low-power mode to a normal mode to supply power to a main control unit of the image forming apparatus, in which the power-supplied main control unit may be used to change the transaction ID. The above-described packet communication may be successfully conducted using a new transaction ID. However, such method may not be desirable in terms of energy saving because power consumption of the image forming apparatus increases in the normal mode. Moreover, typically, a central processing unit (CPU) in a main control unit and a memory of an apparatus consume relatively greater amounts of power.
Consequently, the above-described conventional configuration may not be effective for interactive communication among apparatuses, which may mean that communication can be conducted in only a limited manner. Further, if sophisticated communication is to be conducted using the above-described conventional configuration, information processing apparatuses may consume a relatively greater amount of power, which is not desirable in terms of energy saving.